Detachable door chain



June 19, 1962 MlNTz 3,039,289

' DETACHABLE DOOR CHAIN Filed Dec. 21, 1960 Albert E. Minfz INVENTOR ZMfiW AT TORNE Y United States Patent 9 3,039,289 DETACHABLE DOOR CHAIN Albert E. Mintz, Rego Park, N .Y., assignor of fifty percent each to Robert 0. Richardson, Nashua, N.H., and Dock & Dock, New York, N.Y., a partnership Filed Dec. 21, 1960, Ser. No. 77,430 3 Claims. (Cl. 7093) This invention relates to a detachable door chain and more particularly, it relates to a detachable door chain which is connected between the inside of the door and its frame, yet which can become deteched by an authorized person from the outside.

in my co-pending application, Serial No. 718,035, filed February 27, 1958, and which matured December 27, 1960, into patent No. 2,966,053, of which this is a continuation-in-part, there is disclosed a casing attached to a door frame and a chain releasably mounted to the inside of a door. The chain had a locking plug at the opposite end which was connected to a casing and required a key to separate it therefrom. The chain was of such length that the door could be partially opened to the extent that a key could be passed through from the outside to unlock and remove the plug from the casing.

The detachable door chain comprising the present invention is similar in principle to that of my co-pending application except that in the present instance the locking plug remains connected to the casing on the door frame and the plug locks the chain to the casing or permits separation therefrom as desired. This arrangement has the particular advantage over the embodiment shown in my co-pending application in that the locking plug moves only a short distance within the casing and does not require complete detachment from the casing to provide unlocking. Moreover, the key does not have to pass through the casing but may remain on the key chain of the person using it. Another advantage is that any link in the chain may be connected to the plug to make the length of the chain adjustable to suit the desire of the user. The present arrangement is thought to be easier to operate, is reliable yet simple and inexpensively manufactured.

FIGURE 1 is a prospective view of the detachable door chain as viewed from: the side of the door to which it is mounted,

FIGURE 2 is a side view showing how the chain is secured on the casing, and

FIGURE 3 is an elevational cross-sectional view showing the operation of the locking plug, casing and chain.

Referring now to FIGURE 1, there is shown a fragmentary portion of a door and a door frame 11. The door has a knob 12 and the usual door locks which are not shown in the drawing. In the preferred embodiment of the invention, a door chain 13 is shown attached at one end 14 to the slide part 1-5 which engages a slot 16 in a standard door chain bracket 17 secured to the door 10. The length of the chain 1 3 is such that with the other end 18 aflixed to the door frame 11, the slide part 15 cannot be released from the slot 16 in bracket 17 until the door 10 is substantially fully closed.

The chain end 18 is affixed to door frame 11 through the chain restraining member 19 with a locking plug 20 contained therein. This locking plug 20 passes in front of chain end 18 which has been inserted over a projection 21 better shown in FIGURE 2 and FIGURE 3. Here is more clearly shown the restraining member 19, wall mounting plate 22 with an outward projection 21 integrally formed therewith at the bottom and a casing 23 extending thereover and having an opening 24- into which is fitted a locking plug 21. This locking plug is of such length that it extends down below the casing 23 and in front of the projection =21 to prevent removal of the chain end 18 looped thereover, when the locked plug is in locked position. This locking plug is of the type commonly found in the art wherein a key inserted at one end will cause an outwardly urged locking member 26 to move inwardly to remove it from a recess such as 27 in the mounting plate 212, such that the locking plug may be moved along its axis in the opening 24. To prevent complete removal of the plug from the casing, a groove 27 has been formed in the plug into which a set screw 28 has been positioned. The locking element 26 has a tapered surface 28 which engages tapered surface 29 to depress the locking element 26 upon downward movement of a locking plug to place it in locked position over the chain end 18.

It should now be apparent that the unlocking of the chain and freeing the end 18 from the casing may easily be accomplished by a person on the other side of the door by opening the door Within the limits prescribed by the chain, and then inserting the key into the conveniently located locking plug at the upper end of the casing. With a turning motion and upward movement of the key, the locking plug becomes unlocked and moves upwardly out of alignment with the projection 21 over which the chain end 18 has been placed, and freeing the chain for ready removal to thus unlock the door. Likewise, upon leaving the house, the chain end may be readily placed over the projection and the locking member snapped downwardly by a person on the outside so that the opening of the door would again be restricted by the chain.

It also should be apparent that with the chain end 18 engaging the projection 21 in locked position, the slide part 15 and bracket 17 function in the manner of a conventional door chain, permitting a person on the inside to lock and unlock the door as desired without resorting to the use of a key.

It will be understood that the invention is not to be considered as limited to the use of a slide and bracket at the other end of the chain, since the end 14 of the chain could be secured to the door in a fixed position if desired. The use of the slide and bracket, however, provides greater convenience for the householder by making it possible to release that end of the chain in the conventional manner. Also, if desired, the casing could be secured instead to the door with the other end of the chain fastened to the door frame.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest, possible interpretation within the terms of the following claims.

What is claimed is:

l. A detachable door chain comprising a chain fastened to the inside of a door, and means releasably mounting an end of a chain to the door frame, said means comprising a casing with a locking plug movable therein, said casing having a wall mounting plate with a projection thereon for receiving said end of said chain, said locking plug being movable into cooperative relationship with said projection when in locked position to prevent removal of said chain from said projection, said plug being movable away from said projection to unlocked position to permit removal of said chain from said projection, said chain being of such length as to permit insertion from outside the door of an unlocking means into said locking plug to free said chain when said door, chain and casing are connected.

2. A detachable door chain comprising a chain fastened to the inside of a door, and means releasably mounting an end of a chain to the door frame, said means comprising a casing with a locking plug movable therein, said plug having a locking element thereon, said casing having a wall mounting plate with a projection thereon for receiving said end of said chain, said casing having an opening therein to receive said locking element, said locking plug being movable into cooperative relationship with said projection when in locked position to prevent removal of said chain from said projection, said opening receiving said locking element When said plug is in said locked position, said plug being movable away from said projection in unlocked position to permit removal of said chain from said projection, said chain being of such length as to permit insertion from outside the door of an unlocking means into said locking plug to free said chain when said door, chain and casing are connected' 3. A detachable door chain comprising a chain fastened to the inside of a door, a chain restraining member including a casing with an opening therein substantially parallel to the plane of the Wall on which said casing is mounted, a locking plug fixedly mounted in said opening and having a locking member thereon, said restraining member having means adapted to receive one end of said chain, said locking plug and said restraining member being relatively moveable for selectively restraining and releasing said chain, a recess in said restraining means receiving said locking member to prevent relative movement therebetween, said chain being of such length as to permit insertion from outside the door of an unlocking means into said locking plug to Withdraw said locking member from said recess to permit relative movement between said locking plug and said restraining means and thereby releasing said chain.

References Cited in the file of this patent UNITED STATES PATENTS 

